The Cannonball Alley is an obstacle, firstly introduced as the eighth obstacle during Venice Beach finals on American Ninja Warrior 6.
Competitors must across three different sized balls with their hands. The balls were increasing in size on a slight decline, swinging back and forth from two secured lines.
This obstacle was proven to be brutal, as the first 14 competitors attempted the obstacle with different strategies, but none were successful, gaining a 100% failure rate for most of the night.
It was finally conquered by Kevin Bull, who wrapped his legs around the third ball and swung upside down toward the landing mat, eventually becoming the first finisher of the night.
In total, 16 out of 20 competitors who made it there failed, including top competitors such as Derek Nakamoto, Evan Dollard, Kyle Cochran, and Alan Connealy. The only other three competitors who could complete this obstacle were Dustin Rocho, James McGrath, and David Campbell (who was the last runner and managed to become the second finisher).
The Cannonball Alley returned on American Ninja Warrior 7, as the eighth obstacle during Orlando finals, with a similar specification from Venice Beach finals, except the landing platform was placed higher, which made it harder to complete the obstacle with Kevin Bull's technique.
However, 7 out of 18 competitors could complete the obstacle, including Flip Rodriguez, Travis Rosen, Drew Drechsel, and James McGrath (who also completed this obstacle during American Ninja Warrior 6's Venice Beach finals).
A modified version of Cannonball Alley (called as the Cannonball Incline) appeared as the first obstacle in Stage Three on American Ninja Warrior 6, replacing the Roulette Cylinder from the past two American Ninja Warrior seasons. However, unlike the Cannonball Alley:
- The balls were placed in ascending, with the largest ball in the middle, and
- The balls were only secured by one chain. with the smaller balls swung in any direction.
- After reaching the third ball, competitors must directly make the transition to the next obstacle (the Doorknob Grasper).
However, during USA vs. The World, the balls were enlarged to the same size as the Cannonball Alley. As the result, it ensnared Paul Kasemir (Team USA) and Asa Kazuma (Team Japan). No one else failed it, since they either maintained grip and momentum, or skipped the middle ball altogether.